Deep-drawing of sheet metal



Dec. 29, 1953 c. J. RHODES 2,664,061

DEEP-DRAWING OF SHEET METAL Filed Feb. 4, 1950 4 sheets-sheet 1 lave/1E:

Dec. 29, 1953 I c. J. RHODES 2,564,061

DEEP-DRAWING OF SHEET METAL Filed Feb. 4, 1950' 4 sheet-sneet 2 Dec. 29, 1953 c. J. RHODES DEEP-DRAWING OF SHEET METAL 4 Sheets-Sheet 2':

Filed Feb. 4, 1950 Patented Dec. 29, 1953 UNITED STATES PATENT OFFICE. s i 7 2,664,061

DEEP-DRAWING OF SHEET METAL Charles Joseph Rhodes, Wakefield, England Application February 4, 1950, Serial No..142,404

Claims priority, application Great Britain November 18, 1949 l This invention relatesto improvements in or rel'atingto the deep-drawing of sheet met-a1.

Presses are known in which a female die carried by a ramco-operates with a second die supported on the bed plate of the press, and in which the second die comprises a former" surrounded by an annular member, which latter is supported by a pressure plate beneath the bed of the press, the pressure plate being connected by rack-andpinion means to the former so as to raisethe former against the action of a compression return spring as the annular member and the pressure plate are-depressed by the'descending' upper die during the drawing operation.

Difiiculty is experienced in adapting a press of this known kind to a deep-drawing operation in which a sheet metal blank is first drawn by the former through a drawing ring carried by the mould of the female die, andthen, leaving the drawing ring, is drawn by the former through one or more reducing rings within the female die. W Since pressure is transmitted from thefemale die through the blank to'the annular memher, and thence to the former,- the' blank is gripped so tightly between the female-die and 3 Claims. (Cl. 113-46) the annular member thatit suffers undue strain in being pulled from between these two parts. The use of a'compression return spring also prevents the stroke of theformer being extended at will to suit deeper female dies; Y

According to this invention a press forth deep-drawing of sheet metal comprises a ram, carrying a female die, reciproeable with a working and a return stroketowards and away from a co-operating die, a former in the co-operating die adapted to be projected therefrom into the female die during the working stroke, an annular member surrounding the former and adapted to be depressed bythe female die during the working stroke, and motion-transmitting means, independent of the annular member, operable during the working stroke of the rain to transmit from the ram to the former a motion opposite in direction to that of the -ram.. I

In the press of the'invention, motion is transmitted from the ram to the former independently of the annular member and the pressure with which the blankis gripped between the female die and the annular member is therefore reduced,

so that the metal blank undergoes no undue strain.

Preferably the said motion-transmitting means i are adjustable to become'operative to transmit motion when the female die reaches'a'desired, predetermined'distance from the annular memher during the working stroke.

depths.

' clarity, I

Preferably the said motion-transmitting means are operable during the return stroke of the ram to transmit from the ram to the former a motion opposite to that of the ram, until the former is about to leave the female die and the said mo:- tion-transmtiting means are also operable during the return stroke of the ram to return the annular member towards its starting position. With this arrangement the compression return spring for the former may be replaced by spring means urging the former away from and the annular member towards the ram. The stroke of the former may then be lengthened or shortened as desired to suit female dies of varying One embodiment of the invention will now be described by way of :example with reference to the accompanying drawings, in which: v Fig. 1 is a side elevation of a deep-drawing press according to the invention, the side plate being broken away for clarity.

Fig. 2 is a plan view of the press in Fig. .1, the top'cover plates being removed and the bed and bed-plate of the press shown in section for Fig. 3 is anenlarged sectional plan ofthe press in Figs. 1 and 2 showing'the arrangement of the parts of the press at the bottom of the working stroke, the driving mechanism being omitted;

Fig. 4 is a section on line A-B in Fig. 3, and I Fig. 5 is a fragmentary sectional view of a modified form of female die.

Referring now to the drawings and more particularly to Fig. 3, in'which only such parts of the press are shownas are necessary for the proper understandingof the invention, an adjustable-stroke ram I has a female die 2 exchangeably secured'thereto, the ram being horizontally reciprooable with a working and a return stroke towards and away from a co-operating die 3 secured to the bed-plate 4, which is supported by the bed 5 of the press. The female die 2 comprises a die base 2a, an annular body portion provided with diametrically opposite windows 2b through the lower of which the extruded article falls downwards out of the female die when extrusion is completed. A draw-ring 2c constitutes the mouth of the female die, A reducing or ironing ring 2d and a stripper ring 2e which abut each other, are interposed between the draw-ring 2c and the annular body portion. The drawing-ring 2c, the ironing or reducing ring 2d, the stripper ring 2c, the annular body portion and the die base 2a are secured together by bolts 6.

The co-operating die 8 comprises a base mounted on the bed-plate 4, the bore of the die base being adjacent a large opening 1 in the bed-plate, and an annular member or pressure bush 8 slideable within the bore of the diebase, and free to pass through the opening I in the bed-plate during the working and return strokes of the ram. A horizontal former spindle 9 having a working end 9a exchangeably screwed into the main spindle 9 is slideably carried by a fixed bearing 10 at its end remote from the ram and by a fixed bearing H intermediate its ends, the bearings l and Il being rigidly see cured to the frame of the press. The former spindle 9 is slideable within the bore of the pressure bush 8 and within the bore of the female die 2.

A transmission member in the form of a pressure plate I2 is slideably mounted on the former spindle and bears against the end of the pressure bush remote from the ram through an intermediate pressure block 13, secured to the pressure plate.

The former spindle 9 is reduced in diameter at its end remote from the ram and carries a member l4 concentrically therewith, the member 14 having a set of rack teeth l5 on opposite sides thereof transversely of the central axis of the spindle and rigidly secured to the spindle by a nut I 6 and a locknut I1.

Pinions I3 are rotatably mounted on spindles l8 fixedly carried by a pinion bracket (Fig. 4) which latter is rigidly secured beneath to a pinion bracket support 2| located transversely of the former spindle axis and rigidly secured at each end to side plates 22 and 23 of the press. A cover plate 24 (Fig. 4) is provided on top and is supported at each end by the side plates 22 and 23 and affords easy access to the parts of the press described above.

The pinions l8 are spaced transversely of the former spindle 9 and engage with the rack teeth IS on either side of the member [4 and also engage with rack teeth on the inner surfaces of two parallel spaced rack-members 25 which are each pivotally secured at one end thereof to the pressure plate l2 by pins 26. The rack members 25 are kept in engagement with the pine ions l8 by rollers 21 engaging with the outer surfaces of the rack members, the rollers being rotatably mounted on spindles 28 fixedly carried by the pinion bracket 20. The rack members 25 are each provided on their outer surfaces near their ends adjacent to the pressure plate, with a stepped portion, which latter is under-cut to form a projection 29a, having a vertical abutment face 30 and a second projection 29b having an inclined abutment face 3|. The ends 32 of the rack members 25 remote from the pressure plate are bent outwards at right angles and are provided with openings 33.

The ram l is connected to the bent ends 32 of the rack members 25 through two parallel spaced adjustable turnbuckle links 34 pivotally connected to the ram at one of their ends by pins 35, the other ends being screw-threadedly connected to motion-transmitting members 36 which pass through openings 3! in the bedplate 4 and an opening 38 in the bed of the press, and extend part-way along the press parallel to the axis of the former spindle 9 and adjacent the outer surfaces of the rack members 25. The ends 39 of the members 36 are bent outwardly parallel to the ends 32 of the rack members 25 and are each provided with a slot 40. The ends 39 and 32 are inter-connected by close wound helical springs 4| pivotally connected to the ends 39 of the members 36 by pins 42 and adjustably secured to the ends 32 of the rack members 25 by means of a screw threaded portion passing through the openings 33 and locked in position by screw-threaded nuts 43.

The members 36 are provided on their inner surfaces adjacent the outer surface of the rack members 25 with stepped portions 44, having straight abutment faces 45 and inclined abutment faces 46, the abutment faces 45 and 46 corresponding to the abutment faces 30 and 3| 0! the undercut portion of the rack members 25. Ramps 41 are provided on the outer surfaces of the members 36 intermediate their ends and cam rollers 48 rotatably mounted on pins 49 secured to the bed of the press at either side thereof engage with the outer surfaces of the members 36. The rollers 48 urge the members 36 to engage with the rack members 25 when the ram reaches a predetermined point in its working stroke and assume the positions shown in Fig. 3 when the ram is at the bottom of its working stroke.

The deep-drawing press described above functions as follows:

When the ram l is at the top of the return stroke, 1. e. in the rest position, the working end 9a of the former spindle 9 and the end of the pressure bush adjacent the female die 2 are flush with the end of the base of the co-operating die 3 and a space exists between the mouth of the female die 2 and the co-operating die 3 to permit the insertion of a metal blank. The

turnbuckle links are adjusted so that motion will be imparted to the former spindle 9 in the opposite direction to the motion of the ram. through the motion-transmitting members 38, the springs 4|, the rack members 25, the pinions l8 and the members l4 mounted on the spindle 9, when the female die 2 carried by the ram l reaches a predetermined distance from the pressure bush 3,.

As the ram l carries the female die 2 towards the cooperating die 3, the ramps 41 engage the rollers 48 and swing the motion-transmitting members 36 inwards, so that the steps 44 enter the undercut portions on the outer sides of the rack members 25. When the spacing between the female die 2 and the pressure bush 8 has been reduced tothe above-mentioned predetermined distance, the abutment faces 45 come into abutment with the abutment faces 30 on the rack members 25. Drive is then positively transmitted from the ram through the transmission members 36, rack members 25, pinions l8 and rack members l4 to the former spindle 9, independently of the pressure bush 9. The female die 2 is thus positively spaced from the pressure bush 8 as the blank is drawn by the former 9 through the draw-ring 2c of the female die 2, and the drawn blank can readily escape from between the positively spaced faces of the part: 8 and 2c into the interior of the female die, where it is drawn by the former 9 through the reducing ring 2d and the stripper ring 2e.

As stated above, the female die 2 is allowed to reach a predetermined distance from the pressure bush 8 before the abutment faces 45. come into abutment with the abutment faces 30. This distance may be adjusted to any desired value by adjustment of the turnbuckle links 34. In many cases it will be necessary to adjust the turnbuckle links 34 so that the, said distance is equal to the original thickness of the blank, so that the ab tment faces 45 and 30 come into contact at the same moment as the metal blank is contacted by the draw-r ng 2c and gripped between the latter and the pressure bush 8. The porticn of the metal blank gripped between the parts 20 and d tends to thicken during the initial drawin and the above-described adjustment limits the pressure exerted on the blank by the parts 20 and 8 to a permissible value.

On the return stroke motion is imparted to the former spindle in the oppos te direction to the rain, through the links 34. inclined abutment faces d6. 3!, members 36, rack members 25. pinions i8 and member 14. As the former 9 is retracted from the female die, the extruded metal container abuts against the stripper ring and is positively stripped from the former and falls from the female die throu h the window 21) when the former has been sufficiently retracted.

When the ram reaches a predetermined point in its return stroke, where the working end 9a of the former 9 is about to leave the female die 2, the rollers id roll down the ramps 41, the in clination of the abutment faces 46 on the member s6 and the abutment faces 3| on the rack members 25 urges the members 36 out of engagement with the rack members 25. Thereafter, the former is urged away from the female die and the pressure plate 52 tcgetherwith the pressure bush B3 are urged towards the ram by the springs il. until the ram aga n is at the top of its stroke and in the rest position, thus com leting the cycle of operations.

The above-described arrangement provides for a first drawing operation by means of the drawring 20, followed by a reducing or extruding operation by means of the reducing ring 201. If it is desired to perform a second reducing operation, the exchangeable female die 2 may be replaced by a female die I 02 (Fig. 5) having a draw ring lllzc followed by two spaced reducing rings 5020! and a stripper ring He. The stroke of the ram I must be correspondingly lengthened. and the working end 5a of the former must be exchanged for a correspondingly larger working end.

What I claim is:

1. A press for the deep-drawing of sheet metal comprising a frame, a ram mounted for reciprocation in said frame, a female die carried by said ram, said ram being mounted in said frame for reciprocation co-axially of said female die with a working and a return stroke. a bearing fixed in said frame co-axially of said female die, a former spindle slideable in said bearing into and out of said female die during said working and return strokes respectively, an annular member slideably mounted on said former spindle and cooperating with said female die, a transmission member adiustably mounted on said former spindle, rack-and-pinion means operatively connect ng said transmission member with said former spindle to convert sliding motion of said transmission member into equal and opposite sliding motion of said former spindle, a pair of adjustable-length links pivotally attached to said ram and swingable into and out of engagement with said transmission member, a first abutment face on each link and a corresponding first abutment face on said transmission. member which co operate during the working stroke, a second abutment face on each said link and a corresponding second abutment face on said transmission member which co-operate during the return stroke, said second abutment faces being inclined to urge said links to disengage said transmission member, a pair of rollers mounted on said frame, and ramps on said links co-operating with said rollers to swing said links into engagement with said transmission member at a predetermined point of the working stroke and to hold said link in engagement until the corresponding point of the return stroke is reached.

2. A press for the deep-drawing of sheet metal comprising a a ram mounted for reciprocation in said frame, a female die carried by said rain, said ram being mounted in said frame for reciprocation (ac-axially of said female die with a working and a return stroke, a bearing fixed in said frame co-axially of said female die, a former spindle slideahle in said bearing into and out of said female die during said working and return strokes respectively, an annular member slideably mounted on said former spindle and cooperating with said female die, a pressure plate slideably mounted on said former spindle and bearing against said annular member, a pair of rack members connected to said pressure plate, a pair of pinions mounted on said frame and mesh ing with said rack members, a pair of racks carried by said former spindle and meshing with said pair of pinions, a pair of adjustable-length links pivotally attached to said ram and swingable into and out of engagement with said rack members, a first abutment face on each link and a corresponding first abutment face on each said rack member which (so-operate during the working stroke, a second abutment face on each said,

link and a corresponding second abutment face on each said rack member which co-operate during the return stroke, said second abutment faces being inclined to urge said links to disengage said ra .1 members, a pair of rollers mounted on said frame, and ramps on said links co-operating with said rollers to swing said links into engagement with said rack members at a predetermined point of the working stroke and to hold said links in engagement until the corresponding point of the return stroke is reached.

3. A press according to claim 2, including tension springs connecting the free ends of said links with said rack members.

CHARLES JOSEPH RHODES.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,562,075 Berry Nov. 1'7, 1925 2,341,667 Stacy Feb. 15, 1944 FOREIGN PATENTS Number Country Date 367,503 Great Britain Feb. 25, 1932 

